Devices to connect air conduits used in tractor-trailer braking systems are known. Usually, connectors or valves are mounted on the front section of a trailer for connecting air supplies from the tractor to the trailer braking system. Hose couplings of the gladhand variety are the most commonly employed devices used in both single and double trailer systems. It is also well known in this type braking system to use two pressure conduits, one which is an emergency line or conduit and the other is a service line or conduit. The emergency line is generally charged at all times and the service line is generally charged when the driver applies the brakes by pushing down on the brake pedal in the tractor. Both of the lines lead from the rear of the tractor (since air source is in the tractor) from hoses or other flexible conduits to the trailer or trailers requiring this air source for braking. The forward ends of the trailer emergency and service lines terminate at gladhands and it is important that the tractor lines and gladhands be connected to the appropriate valves for the service and emergency lines of the trailer. This coupling of gladhand and shutoff cock (valve) requires the constant connection, disconnection, repair and replacement of the coupling components. Since the shutoff cock or valve has the more complex and detailed construction including air intakes and air ports, conduit connectors, air chambers, camming surfaces, movable valve handle, etc., it is more likely to become worn or corroded upon continued use. It is not uncommon for this metallic valve to become corroded and to freeze up so that it needs to be frequently replaced. This is true of both the service and emergency valves. Thus, the truck operator needs to keep several relatively expensive service valves and several emergency valves in stock since they have different constructions and cannot be used interchangeably. Also, since valves of different manufacturers must be compatible with each other because of standard usage, it has not been practical to change or modify the valves to any great extent. These valves, for example, may be used or coupled with components of another manufacturer and must always be compatible therewith. Therefore, any improvement in design or construction of these valves that would significantly improve their longevity, requires less inventory be held in stock or reduces their costs would be an important step forward in the art.
There are known several coupling devices used in tractor-trailer braking systems such as those disclosed in U.S. Pat. Nos. 3,052,489: 3,241,865; 3,960,365 and 4,550,928. In U.S. Pat. No. 3,052,489 (Stoudt) a coupling member is disclosed having a unitary coupling means with a lock arm for each coupling and provisions made for easier assembly. By employing strip steel in lieu of the rigid lock arms employed before, merely a stamped indentation provides sufficient detent locking without the necessity of any separate detent means as previously required. In Stoudt as in the other references noted above, separate valves are needed for use, one as an emergency valve and the other as a service valve. Users must keep an adequate supply of both in inventory for replacement of corroded or worn valves. Also, Stoudt is concerned only with couplings to be used between the tractor and a single trailer to be hauled. No shutoff valve or handle is required in Stoudt since a shutoff valve is only required when two trailers are to be hauled in tandem. The shutoff valve in a coupling device is used primarily as a two trailer hookup and is turned off (supply of air) when the vehicle is not moving or where only one trailer is going to be hauled.
In Pumphrey, U.S. Pat. No. 3,241,865, the use of both a service and an emergency valve is disclosed with each having means to prevent mismatching of couplings- Prior to Pumphrey, the letters "S" and "E" were stamped on the service and emergency respectively to distinguish each. Pumphrey provided unique abutments or lugs which were incompatibly positioned for preventing the wrong valve to be coupled, i.e. service valve with emergency gladhand, etc. Mismatching, therefore, of the emergency or service valves, especially in the dark was avoided by Pumphrey's invention. But Pumphrey taught the use of two separate valves, an emergency valve and a service valve. Also, Pumphrey, as all other valves disclosed by the noted prior art, are susceptible to corrosion after prolonged use. The coupling devices in all tractor-trailer usages are exposed to the elements such as rain and snow and can easily become corroded and rendered inoperative. This is true especially with moving parts of a valve such as the shutoff handles, etc. Therefore, Pumphrey's valve is limited to use in single trailer hookups, uses both separate emergency and service valves and, as are the other prior art valves, constructed of materials that will rust or corrode upon extended use.
In U.S. Pat. No. 3,960,365 (Horowitz), a combination gladhand and shutoff cock is disclosed for use on tandem or doubles operation. The gladhand used by Horowitz has a shutoff cock and a fitting positioned within a passage of the gladhand. This fitting is used in making a connection with a conduit on the trailer and also used is a spring-biased bushing between the fitting and shutoff cock for forming a seal. Horowitz discloses the use of valves which are similar in construction, except for the spring-biased bushing, to conventional valves used in tandem operations, i.e. emergency and service valves. Horowitz's device, unlike the others noted in the above patents, is useful in the rear of a trailer which will pull a second trailer.
Berg, U.S. Pat. No. 4,550,928 discloses a front air swingaway for connecting an air supply between a tractor-trailer combination. The swingaway is adapted to be mounted on the front of a trailer and projects forwardly when in use. It is automatically folded back against the front of the trailer when not in use, i.e. when it is not connected to a gladhand. Berg, however, is not concerned with use in a tandem operation but is rather limited for use when a single trailer is being hauled.
All of the above-discussed references except for Horowitz are concerned only with single trailer use, thus, shutoff cocks are not required in their devices. The present invention is adapted for use in tandem operations and thus requires a shutoff cock or component. All of the references discussed teach the use of conventionally constructed metallic valves, both service and emergency valves. These valves are, as noted earlier, are susceptible to rusting and corrosion from moisture, salt and the like. In addition, all references noted require the inventory supplies of both service and emergency valves since in the prior art they are not interchangeable.